The objective of the proposed reseach is to study the effects of sensory deprivation on the visual system of primates. In particular the effect of monocular and binocular lid closure on the anatomy, electrophysiology and behavior of a prosimian primate, Galago senagalensis, will be studied. Where deemed appropriate comparisons will be made between similar studies in tree shrew, Tupaia glis and owl monkey, Aotus trivirgatus. In brief the following approaches will be used: (1) The anatomical changes caused by deprivation will be determined through measures of cell size in the lateral geniculate nucleus, cell packing density in the superior colliculus and visual cortex; and changes in distribution of retino-geniculate and geniculo-striate axons. (2) The responses of single neurons in the dorsal lateral geniculate nucleus of normal galagos will be determined and compared to those in deprived animals. (3) Behavioral changes caused by lid suture will be determined in galago and tree shrew through tests of visual perimetry.